1. Field of the Invention
The present invention relates to a brine refrigerating apparatus in which brine is used as a coolant.
2. Description of Related Art
It is preferable to keep foodstuffs, such as perishables or raw noodles in cold storage at a constant temperature and high humidity. It is difficult to realize such an isothermal atmosphere of high humidity using a refrigeration cycle in which cooling is effected by a phase change of the coolant. Because of this difficulty, a brine refrigerator has been used, in which brine having a high latent heat is used as a coolant.
In a conventional brine refrigerator, cooled brine is circulated along wall surfaces of a refrigerating chamber. There are two known types of cooling systems, one of which has four cooling surfaces of right and left side surfaces, an upper surface and back surface, and the other having five cooling surfaces of right and left side surfaces, an upper surface, back surface and bottom surface. In the brine refrigerators, a difference in temperature between the cooling surfaces and the cooling chamber can be decreased to increase the dew point temperature of the cooling surfaces, thereby resulting in high humidity.
In the known brine refrigerators, it is possible to restrict the fluctuation of temperatures in the refrigerator within 1.degree. C. due to convection of the cold air at no load in which no foodstuff is put in the refrigerator. It has been found, however, that when foodstuffs fill the cooling chamber, it is impossible to realize an ideal storage condition due to a temperature difference of the foodstuffs. This is because when the cooling chamber is filled with the foodstuffs, no effective convection of the cold air takes place, so that the foodstuffs are cooled only by the heat transmission between the foodstuffs and the wall surfaces of the cooling chamber. To solve this problem, it is necessary to provide a large dead space in the cooling chamber in order to decrease the temperature difference in the cooling chamber, thus resulting in a decreased cooling efficiency.
Perishables have different inherent optimum storage temperatures depending on the kind thereof. However, in the conventional refrigerator in which a low temperature chamber is located at an upper portion of the refrigerator and a vegetable storing chamber of a relatively high temperature is located at a lower portion of the refrigerator, there is no distribution of different storing temperatures, which depend upon the particular foodstuffs being refrigerated. For example, in a conventional three-door refrigerator or four-door refrigerator, there is a distribution of temperatures of "below -10.degree. C.", "approximately 0.degree. C.", "approximately 5.degree. C.", and "approximately 10.degree. C.". Namely, it is impossible to provide a temperature distribution of a pitch of 1.degree..about.2.degree. C. between -1.degree. C. and 10.degree. C.